She added: “I would be absolutely heartbroken if anything happened to it.”

Mary was recovering from a hip replacement operation in Kirkcaldy’s Victoria Hospital when her eldest daughter, Michelle, gave her the balloon as a gift on October 5, 1995.

The mum of four got out of hospital 10 days later and took the balloon to her home in Pitcoudie, Glenrothes , where it has remained ever since.

Helium balloons usually retain their shape for a few days but Mary’s bear​, which is now attached to a stick, continues to astonish her friends and family.

Mary's daughter Nicola in 2001 with the balloon behind her

She said: “It has been solid the whole time. It was originally stuck in with a rubber plant in the living room but when the plant died, I put it in with an orchid in the kitchen.

“I think it gets its energy from the plants.

“When we tell people how long we’ve had it, they are absolutely amazed. And it’s still as firm as the day I got it.”

To put the balloon’s longevity into context, it is older than Mary’s five grandchildren – the eldest of whom is 17.

Today, it is kept on top of a tumble dryer but Mary, who lives with husband Douglas, 65, says she is always ultra-cautious when working around it.

She added: “When I put the dryer on, I always move the balloon.

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“I don’t want to take the chance that it could go flying off. I suppose it has become part of the family.”

The balloon was bought by Michelle, 42, in the WRVS shop at the Victoria Hospital. It spent the best part of 17 years in Mary’s living room, alongside her rubber plant. It was then moved to the kitchen, where it was paired with an orchid.